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Walking into the Marine Geology Repository at Oregon State University is like taking a journey into the past.

A combination of research lab and warehouse, the repository provides climate-controlled storage space for thousands of geological samples collected over the last several decades by OSU researchers.

The bulk of the collection is composed of nearly 6,200 sediment cores neatly labeled and arranged on racks in a giant walk-in refrigerator set to 38 degrees Fahrenheit. Most were drilled out of the ocean floor, with the rest taken from freshwater environments.

While some contain sediments laid down in the relatively recent past, others date back as much as 50 million years — not long after humanity’s earliest primate ancestors first appeared on the planet.

It’s one of only about 10 such repositories in the country and boasts the largest collection of marine sediment cores on the West Coast.

Each core sample starts as a cylinder that is then cut into 5-foot sections. Each section is cut in half the long way, with one half designated for research and the other set aside to be permanently archived.

“If you took each of the sections and laid them end to end, it’s just under 20 kilometers,” said Maziet Cheseby, the repository’s curator. “It would be like from here to Albany.”

Funded in part by the National Science Foundation, the repository makes samples from the sediment core available to researchers from across the country and around the world. It can also perform various types of analysis on the samples, looking for properties such as physical structure, chemical composition, organic content, magnetic orientation and age.

That information can be used in a wide variety of ways, from chronicling ancient geological events to providing clues about changing atmospheric conditions in the distant past.

“By looking at these sediments, it provides a way to go back in time. They’re kind of like time machines,” said Joe Stoner, an associate professor of marine geology at OSU and the repository’s principal investigator.

“They’re also like a solutions manual to the Earth,” Stoner added. “They tell us how it operates and how it did operate and could operate under different conditions.”

One of Stoner’s own samples is a case in point. Collected by his team in 2013 from Fish Lake on Steens Mountain in far southeast Oregon, the core captures a snapshot of the region’s past going back some 13,000 years, to about the end of the Pleistocene Era.

Most of the sample looks like dark-brown mud, exactly what you’d expect from lake-bottom sediment. But toward the bottom is an inch-thick stripe of gray material, with a thinner strip of the same stuff a little below that.

The big gray stripe, Stoner explains, is a deposit of tephra, or volcanic ash, from the eruption of Mount Mazama, a cataclysmic event that occurred around 5700 BC and created what we know today as Crater Lake.

“There’s a number of other tephras in here,” Stoner said. “Some of them are thought to be from Medicine Lake, others could be from Newberry Crater, and there are some from Diamond Lake.”

Stoner’s primary research interest in the sample has to do with how the Earth’s magnetic field has changed over time, a phenomenon that remains poorly understood.

But the thousands of samples in OSU’s collection can provide valuable information about a host of other natural processes as well, including how the planet’s climate has changed over time and what impacts that has had on living organisms.

Examining the past, Stoner said, can give us a glimpse of what to expect in the future.

“With our CO2 levels at 400 parts per million, we are moving toward a more distant past. Right now we are at CO2 levels equivalent to where we were 3 to 4 million years ago,” Stoner said.

By examining some of the geological samples from that period, he said, “we can learn something about how the Earth worked at higher CO2 levels.”

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Reporter Bennett Hall can be reached at 541-758-9529 or bennett.hall@lee.net. Follow him on Twitter at @bennetthallgt.

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Special Projects Editor

Special Projects Editor, Corvallis Gazette-Times and Albany Democrat-Herald